Large-scale structure and the intrinsic alignment of galaxies

TL;DR

This paper develops and tests a model for intrinsic galaxy alignments, demonstrating its effectiveness in explaining data and providing a method to reduce IA contamination in weak lensing surveys.

Contribution

The paper introduces a tidal alignment model for intrinsic alignments and a technique to separate IA from lensing signals, improving weak lensing analysis accuracy.

Findings

The tidal alignment model successfully describes observational IA data.

The separation technique constrains IA contamination to below a few percent.

Application to SDSS data validates the model and method.

Abstract

Coherent alignments of galaxy shapes, often called "intrinsic alignments" (IA), are the most significant source of astrophysical uncertainty in weak lensing measurements. We develop the tidal alignment model of IA and demonstrate its success in describing observational data. We also describe a technique to separate IA from galaxy-galaxy lensing measurements. Applying this technique to luminous red galaxy lenses in the Sloan Digital Sky Survey, we constrain potential IA contamination from associated sources to be below a few percent.